Problems in the Baltimore Police Department drew scrutiny well before the Department of Justice released its withering report on the agency Wednesday.

In the report, the result of a 14-month investigation, the Justice Department accused officers of using undue force, discriminating against African-Americans, mishandling sexual assault cases, using Tasers excessively and without justification, and failing to meaningfully investigate complaints of police misconduct.

Those actions, the Justice Department concluded, amounted to a "pattern or practice of conduct that violates the Constitution or federal law."

But the Justice Department was not the first to look into these issues.

Zero-tolerance policing

Zero-tolerance policing has been controversial since Martin O'Malley embraced it as mayor from 1999 to 2007.

Critics of the approach, which involves frequent stops and searches of pedestrians, and strict enforcement of minor offenses, say it punishes African-Americans disproportionately and leads to police brutality.

A selection of The Sun's coverage of the Baltimore Police Department since 2014. Findings of the Justice Department probe of the police department -- which was launched after the April 2015 death of Freddie Gray -- will be released Wednesday, according to sources familiar with the probe.

The Baltimore Sun has explored the effectiveness and ethics of zero-tolerance policing going at least as far back as 1999, including stories filed from New Orleans and New York City, where police departments had adopted the approach.

In Baltimore, the practice raised arrest numbers dramatically and drew mounting opposition from civil rights advocates and prosecutors. The ACLU and the NAACP sued the city in 2006 over its policing practices. The city settled the suit in 2010 and agreed to move away from zero-tolerance policing.

Current Police Commissioner Kevin Davis has spoken critically of the approach. "Some of things that we did in the past, like zero-tolerance policing, didn't work and arguably led in part to the unrest that we experienced in 2015," Davis told NPR.

The Department of Justice said zero-tolerance policing resulted in "repeated violations of the constitutional and statutory rights" of city residents, and hurt relations between the police and the community.

Unfounded rapes

The Sun published an investigation into the Police Department's handling of rape complaints in 2010.

In a review of four years of FBI and police data, The Sun found that the department dismissed a greater percentage of rape allegations as baseless or false than police in any other city in the country. Officers tasked with fielding rape complaints dismissed 40 percent as unfounded, precluding further investigation.

And in a more than 10-year period, the number of rapes reported by the Baltimore police fell by nearly 80 percent. Nationally, rapes fell only 8 percent in that period.

At the time, Mayor Stephanie Rawlings-Blake told The Sun she was "deeply troubled" by the statistics. The city created a Sexual Assault Response Team to oversee the department's handling of such cases.

Still, the Department of Justice report, which reviewed the years from 2010 through 2015, was critical of the police response to sexual assault allegations. The Police Department "seriously and systematically under-investigates reports of sexual assault," the Justice Department found. Such investigations are often delayed and mishandled, the Justice Department said, perhaps reflecting a gender bias in the agency.

Police brutality

The Baltimore Sun examined allegations of police brutality in the city in 2014.

The six-month investigation found that the department had paid out $5.7 million in taxpayer money to more than 100 litigants who claimed police officers had used excessive force.

The alleged victims included a 15-year-old boy on a dirt bike and a 50-year-old woman selling church raffle tickets. Most were African-American. Some officers had been accused of brutality in as many as five lawsuits.

"These officers taint the whole department," City Council President Bernard C. "Jack" Young said at the time. "I'm tired of the lawsuits that cost the city millions of dollars by some of these police officers."

The Justice Department also found that city police use "excessive" and "unreasonable force," including against people who were detained, had mental health problems or did not pose an immediate threat. The Justice Department said officers "unnecessarily escalate encounters."

Shocking force

The Sun published a six-month investigation into the use of Tasers by police forces throughout Maryland in March.

Reviewing every incident in which an officer had used a Taser between 2012 and 2014, the Sun found that police in the state had not followed safety recommendations of both experts and Taser's manufacturer, and had routinely used a Taser on people who posed no immediate threat.

Maryland lawmakers called for a statewide policy on Taser use by police.

The Justice Department said Baltimore police have frequently used Tasers in ways that are "unnecessary and unreasonable." Officers have used Tasers on juveniles, detainees, people with mental health issues and others without justification, the department said. Officers have also used Tasers as retaliation, the department said.

Police accountability

The Sun published an investigation this month into the Police Department's internal affairs unit, which reviews allegations of police misconduct.

An examination of more than 1,700 complaints from citizens and other police officers from January 2013 to March 2016 showed that the department took eight months on average to complete these cases, and that most that it did complete were inconclusive.

The Sun found that these investigations substantiated allegations of excessive force only rarely, at a rate below the national average.

Commissioner Davis told The Sun at the time that he was "absolutely confident our Police Department will be a model for police accountability in short order."

The Justice Department also criticized the police force's complaint review procedures, which it described as "plagued by systemic failures." Officers discouraged residents from filing complaints, failed to punish wrongdoers on the force, mismanaged investigations, and completed them too slowly, the department said.

Davis promised reform following the release of the Justice Department report. "I know it's an opportunity to get better," he told The Sun Wednesday. "It's not a suggestion," he said. "It's compelled and mandated. That's what changes things."